Log message:
math: Replace RMD160 checksums with BLAKE2s checksums

All checksums have been double-checked against existing RMD160 and
SHA512 hashes

Log message:
math: Remove SHA1 hashes for distfiles

Log message:
Update all R packages to canonical form.

The canonical form [1] of an R package Makefile includes the
following:

- The first stanza includes R_PKGNAME, R_PKGVER, PKGREVISION (as
  needed), and CATEGORIES.

- HOMEPAGE is not present but defined in math/R/Makefile.extension to
  refer to the CRAN web page describing the package.  Other relevant
  web pages are often linked from there via the URL field.

This updates all current R packages to this form, which will make
regular updates _much_ easier, especially using pkgtools/R2pkg.

[1] http://mail-index.netbsd.org/tech-pkg/2019/08/02/msg021711.html

Log message:
Add the CRAN archives to R package MASTER_SITES.

Distfiles for older R packges are moved on CRAN from contrib/ to
contrib/Archive/${R_PKGNAME}/.  As a result, they may be inaccessible to
'make fetch'.  Add the additional directory to MASTER_SITES in
math/R/Makefile.extension so that older distfiles will be retrieved
directly from CRAN.  In addition, remove the definition of MASTER_SITES
from math/R-prob/Makefile, which is the only package directly referring to
the distfile archive.  At this point all R packages should rely on
math/R/Makefile.extension to define MASTER_SITES; they should not be
defining MASTER_SITES directly.

Log message:
math/R-prob: Import version 1.0.0

A framework for performing elementary probability calculations on
finite sample spaces, which may be represented by data frames or
lists.  Functionality includes setting up sample spaces, counting
tools, defining probability spaces, performing set algebra,
calculating probability and conditional probability, tools for
simulation and checking the law of large numbers, adding random
variables, and finding marginal distributions.  Characteristic
functions for all base R distributions are included.